On what would have been Maureen O'Hara's 99th birthday, a recently discovered love letter to the star has been revealed.

O'Hara's grandson, Conor Fitzsimons, found the letter in an old book while he and his family were moving house.

It was written by Irish American director John Ford ahead of the filming of the Quiet Man in Ireland.

"She used to hide things in books," Fitzsimons told RTÉ Radio 1.

"We were putting books away and we found an old book that would have been the old Quiet Man story. We opened it up and there in the middle of the book was this old letter. We were taken aback by it.

"We brought it to Ireland because I wanted to find a date on it. I wasn't sure when exactly it was written."

Forde wrote the note to the actress on headed paper from Ashford Castle in Co Mayo while researching filming locations.

John Ford and Maureen O'Hara in Ireland during the filming of The Quiet Man.

A portion of the letter published in the Irish Times reads:

Oh Maureen, my darling, I love you so much! Thank you my love for the few months happiness you have given me. I miss you so much. God, I long for you. I dream of you. Your face is constantly in my dreams.

"It was a kind of 'cheek and tongue' love letter," Fitzsimons said.

"I think he was enamoured by my grandmother his whole life so when he was there in 1950 he must have written the letter to her. There's a few letters he wrote to her from different hotels while he was scouting the Quiet Man."

Fitzsimons said Ford's feelings were not returned by O'Hara.

"I would say it was one way. Ford was probably enamoured with my grandmother. Most men yearn for the one thing they can't have.

"Ford was alway enamoured with Maureen, that's why he used her so many times in so many movies."

He said his grandmother had a strong friendship with Ford and with her co-star John Wayne.

"They were such good friends behind the scenes, Ford and John Wayne and Maureen. They used to spend a lot of time at Ford's house singing Irish songs. The friendship was so much beyond the screen between the three of them."

A scene from 'The Quiet Man'

Fitzsimons described Ford's feelings for his grandmother as "a schoolboy crush"

"It was kind of like a schoolboy crush. Ford wrote her a good few letters. Two of them are on display at the Shelbourne. There's been a few other letters that we found that were auctioned off in New York in 2014. Every time we open a box we come across theses random letters she had stashed away from the world."

He said the family will auction off the recently found letter and donate the money to a number of charities.

Meanwhile, her adopted home of Glengarriff in west Cork will unveil a €60,000 life-size bronze statue of the iconic, Dublin-born actress ahead of the 100th anniversary of her birth. The statue will be unveiled on August 17 next year.

The project is being jointly funded by Fitzsimons, Glengarriff Tourism Association, and Cork County Council. She lived in the village from 1968 until 2014.